[SPv2] Adds pre-computed paint property context to PaintLayer.

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index f48b8772ce4a0e0500b69506c1569b7940b483ce..611f9fd79712c005f92863e7d024d7627b2e2af5 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -310,6 +310,20 @@ static void updateOutOfFlowContext(const LayoutObject& object, bool createdNewTr
     }
 }
 
+PassOwnPtr<ObjectPaintProperties::PropertyTreeContext> cacheTreeContextIfNeeded(LayoutObject& object, const PaintPropertyTreeBuilderContext& context)

[pdr., 2016/02/04 00:06:45]

I still don't really view this as a cache any more than the entire tree is a
cache for efficiently looking up property data.

Rename createAncestorContextIfNeeded? (or similar)?

[trchen, 2016/02/04 00:51:29]

recordTreeContextIfNeeded that is.

+{
+    // Note: Currently only layer painter makes use of the cache. This condition can be changed.
+    if (!object.hasLayer())
+        return nullptr;
+
+    OwnPtr<ObjectPaintProperties::PropertyTreeContext> contextCache = adoptPtr(new ObjectPaintProperties::PropertyTreeContext);
+    contextCache->paintOffset = context.paintOffset;
+    contextCache->properties.transform = context.currentTransform;
+    contextCache->properties.clip = context.currentClip;
+    contextCache->properties.effect = context.currentEffect;
+    return contextCache.release();
+}
+
 void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
 {
     PaintPropertyTreeBuilderContext localContext(context);
@@ -318,6 +332,7 @@ void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTre
     RefPtr<TransformPaintPropertyNode> newTransformNodeForPaintOffsetTranslation = createPaintOffsetTranslationIfNeeded(object, localContext);
     RefPtr<TransformPaintPropertyNode> newTransformNodeForTransform = createTransformIfNeeded(object, localContext);
     RefPtr<EffectPaintPropertyNode> newEffectNode = createEffectIfNeeded(object, localContext);
+    OwnPtr<ObjectPaintProperties::PropertyTreeContext> newContextCache = cacheTreeContextIfNeeded(object, localContext);
     RefPtr<ClipPaintPropertyNode> newClipNodeForOverflowClip = createOverflowClipIfNeeded(object, localContext);
     // TODO(trchen): Insert flattening transform here, as specified by
     // http://www.w3.org/TR/css3-transforms/#transform-style-property
@@ -325,14 +340,15 @@ void PaintPropertyTreeBuilder::walk(LayoutObject& object, const PaintPropertyTre
     RefPtr<TransformPaintPropertyNode> newTransformNodeForScrollTranslation = createScrollTranslationIfNeeded(object, localContext);
     updateOutOfFlowContext(object, newTransformNodeForTransform, localContext);
 
-    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation) {
+    if (newTransformNodeForPaintOffsetTranslation || newTransformNodeForTransform || newEffectNode || newClipNodeForOverflowClip || newTransformNodeForPerspective || newTransformNodeForScrollTranslation || newContextCache) {
         OwnPtr<ObjectPaintProperties> updatedPaintProperties = ObjectPaintProperties::create(
             newTransformNodeForPaintOffsetTranslation.release(),
             newTransformNodeForTransform.release(),
             newEffectNode.release(),
             newClipNodeForOverflowClip.release(),
             newTransformNodeForPerspective.release(),
-            newTransformNodeForScrollTranslation.release());
+            newTransformNodeForScrollTranslation.release(),
+            newContextCache.release());
         object.setObjectPaintProperties(updatedPaintProperties.release());
     } else {
         object.clearObjectPaintProperties();